Hitherto, in battery-driven electronic devices in which two AA size batteries are power sources, various types of batteries can be used.
In the case of an AA size battery, for example, two alkali batteries, two nickel primary batteries, or two nickel secondary batteries can be used. In the case of a box-type battery, for example, a lithium primary battery or a lithium secondary battery can be used.
However, there is a large difference in the power capacities and the characteristics of these batteries. For example, between two alkali AA size batteries and a lithium secondary battery, there is a large difference in the power capacities, the impedance at low-temperature time, and impedance characteristics when the battery voltage is decreased.
More specifically, in spite of the fact that the difference in the characteristics of batteries is large, current battery-driven electronic devices always operate under the same conditions irrespective of the type of battery. For this reason, even with a battery of a high capacity and a low impedance like a lithium primary battery, there are problems in that the potential thereof cannot be fully exploited.